There currently exists a number of mechanisms and methods for tightening a shoe or boot around a wearer's foot. A traditional method comprises threading a lace in a zig-zag pattern through eyelets that run in two parallel rows attached to opposite sides of the shoe. The shoe is tightened by first tensioning opposite ends of the threaded lace to pull the two rows of eyelets towards the midline of the foot and then tying the ends in a knot to maintain the tension. A number of drawbacks are associated with this type of lacing system. First, laces do not adequately distribute the tightening force along the length of the threaded zone, due to friction between the lace and the eyelets, so that portions of the lace are slack and other portions are in tension. Consequently, the higher tensioned portions of the shoe are tighter around certain sections of the foot, particularly the ankle portions which are closer to the ends. This is uncomfortable and can adversely affect performance in some sports.
Another drawback associated with conventional laces is that it is often difficult to untighten or redistribute tension on the lace, as the wearer must loosen the lace from each of the many eyelets through which the laces are threaded. The lace is not easily released by simply untightening the knot. The friction between the lace and the eyelets often maintains the toe portions and sometimes much of the foot in tension even when the knot is released. Consequently, the user must often loosen the lace individually from each of the eyelets. This is especially tedious if the number of eyelets is high, such as in ice-skating boots or other specialized high performance footwear.
Another tightening mechanism comprises buckles which clamp together to tighten the shoe around the wearer's foot. Typically, three to four or more buckles are positioned over the upper portion of the shoe. The buckles may be quickly clamped together and drawn apart to tighten and loosen the shoe around the wearer's foot. Although buckles may be easily and quickly tightened and untightened, they also have certain drawbacks. Specifically, buckles isolate the closure pressure across three or four points along the wearer's foot corresponding to the locations of the buckles. This is undesirable in many circumstances, such as for the use of sport boots where the wearer desires a force line that is evenly distributed along the length of the foot. Another drawback of buckles is that they are typically only useful for hard plastic or other rigid material boots. Buckles are not as practical for use with softer boots, such as ice skates or snowboard boots.
There is therefore a need for a tightening system for footwear that does not suffer from the aforementioned drawbacks. Such a system should automatically distribute lateral tightening forces along the length of the wearer's ankle and foot. The tightness of the shoe should desirably be easy to loosen and incrementally adjust. The tightening system should close tightly and should not loosen up with continued use.